1. Field of the Invention
The present invention relates to microwave dielectric ceramics and more particularly to microwave dielectric ceramics being sintered at low temperature and having improved microwave properties and a method of producing the same.
2. Description of the Prior Arts
Wireless communications devices comprise both passive and active components, the former in greater quantity that the latter. However, passive components are very expensive and may account for 70% of the cost of the communications device. Furthermore, integrating passive components allows miniaturized and lightweight communications devices. However, passive components generally comprise dielectric ceramics with very high sintering temperatures (in excess of 1300° C.) and electrodes. Therefore, silver or copper cannot be used. The electrodes must either be expensive platinum or silver palladium alloys.
Current research is directed toward microwave dielectric ceramics co-sintered with conductive metals, referred to as low temperature co-sintered ceramics (LTCC), and having the following advantages:
1. Low sintering temperature (less than 1000° C.).
2. Ceramics can be co-sintered with metals such as gold, silver and copper so forming ceramics with low impedance and low dielectric constant loss for lower cost.
3. A manufacture layer of the ceramic is not limited.
4. Resistors, capacitors and inductors are mounted in the ceramics.
5. Low thermal expansion coefficient and water absorption.
Therefore, LTCC is a good material for high-frequency communications components.
LTCC are classified by the major material of the ceramic, and include BaO—TiO2—Re2O3, Bi2O3, BaO—TiO2, MgO—TiO2, CaO—TiO2, ZnO—TiO2, Zn—SnO2—TiO2, BaO—WO3—CuO and CuO—ZrO2. An agent is added to the LTCC to promote a low melting point glass phase and reduce the sintering temperature of the ceramics. However, the agent can decrease microwave properties of the LTCC.
However, LTCC still has a high sintering temperature so remains costly and a highly energy dependent process.
To overcome the shortcomings, the present invention provides a microwave dielectric ceramics and method for manufacturing the same to mitigate or obviate the aforementioned problems.